1998 Chevy Blazer shutting down on long drives

Tiny
JAULT01
  • MEMBER
  • 1998 CHEVROLET BLAZER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 136,000 MILES
I was driving for about two hours, about 90 miles from home when I noticed suddenly that I could not accelerate. (It was the middle of the day and hot outside.) When I hit the gas the car sputtered (like it was missing almost) and came to a hault.

After letting the car set for a half hour it would start up, after which I'd get about 5 miles and it would happen again. I finally limped it to a parts shop where I got a reading saying that O2 sensors bank one sensors 1 and 2 were reading low voltage.( I have four O2 sensors) I replaced them and drove about 50 miles home without trouble. (When I drove home it was dark and cool outside.) I also drove about 40 miles that evening without any signs of trouble.

I continued through the week, any hour of the day, without trouble. My average drive was only about 10 miles.

A week later, this time 100 miles away and in the dead of a summer day, it happened again. This time I allowed the car to set about a half hour, it made it about 5 miles and shut down again. I got another reading, and it showed the same error on the same O2 sensors. ( I only unplugged the battery for about 5 minutes, perhaps the computer didn't reset?) I let the car set for several hours until it started to cool down outside and I drove about 80 miles home without any trouble again.

I've replaced two of 4 O2 sensors (which read low voltage) and aside from that I have no clue. I've checked the Catalytic converter after short trips and it didn't seem to be glowing. What should I look for next? It seems to only happen when it's hot outside and I have driven for over 80 miles.

I recently replaced the radiator, about a week before the first incident.

Any ideas? I would greatly appreciate your help!

Jeff
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Saturday, June 12th, 2010 AT 10:23 PM

9 Replies

Tiny
SCOTTY DEE
  • MEMBER
Get a fuel pressure gauge and throw it in the blazer. The next time that happens, be prepared to test the fuel pressure.

Hook up your gauge before you take off so you know where to tie in, and also to determine if the pressure may be on the low end of the threshold to begin with.

Keep me posted.
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Wednesday, June 16th, 2010 AT 7:22 AM
Tiny
JAULT01
  • MEMBER
Will do, Scotty. I take it that you suspect that the fuel pump may be malfunctioning? I wondered that myself, it just seemed odd that it would do it "circumstantially" like that.

I managed to clear the "O2 sensor low voltage" reading as well. I only had one of the scan tools from autozone to help me out.

I also ran it for about 30 minutes and tapped on the ignition control module to see if it shorted out, it kept running.

I'm going to go and get one of those gauges and run the car for 80 or so miles again to see what happens. I'll be back in touch!

Thanks for helping!
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Wednesday, June 16th, 2010 AT 4:04 PM
Tiny
SCOTTY DEE
  • MEMBER
It's my first suspicion, O2 sensors won't make one die like that.
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Wednesday, June 16th, 2010 AT 5:27 PM
Tiny
JAULT01
  • MEMBER
The reason I referred to the 02 sensors is because that is what the scan showed when I had the check engine light. I haven't seen the light nor the issue reoccur since I reset the computer, but then again I haven't been on a long trip. I'm still waiting for a call about a loaner gauge to test my pressure.

I just checked my #2 spark plug, it seems to have a bit of carbon fouling. I guess that this is a result of the bad sensors, correct? (The sensors determine the mix with the computer?) I know that typically a fouled plug will lead to problems like sluggish performance, and misfiring. Could this eventually cause a stall on a long trip? (Doubtful, but I thought I'd ask.)

I was also wondering what the resistance on a fuel pump relay should read with a multimeter. I thought that it should be infinite when you read with a 200 Ohm setting, but mine reads 88 cold and 93 or so when its warm.

Sorry to bombard you with questions, I just want to be sure that I am checking things properly!
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Wednesday, June 16th, 2010 AT 6:10 PM
Tiny
SCOTTY DEE
  • MEMBER
You're doing fine. I think fuel pressure is where we want to go for now.
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Thursday, June 17th, 2010 AT 8:28 AM
Tiny
JAULT01
  • MEMBER
Scotty:

Without leaving the driveway the pressure at idle is between 52-54 psi (the needle was bouncing a bit.) And when I gave it gas, it was 50.

Before starting the car (ignition in the on position, the reading was 58 or so.)

When the ignition was turned off, the pressure held. So no leaks, right?

AllData says that the spec is 55-60 idle and 66 open throttle

Pressure before the filter is 80 psi, same with open throttle

I'm having trouble locating the pressure regulator. To test that. I've looked under there, I see something with a vacum hose attached, with an electrical component from the manifold to the top of it. Is that it? All Data is very vague.

Bad filter?

Thanks,

Jeff
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Thursday, June 17th, 2010 AT 2:01 PM
Tiny
JAULT01
  • MEMBER
Ok

So I drove it for 2 hours, and 85 miles (which is about the same amount of time that it took it to shut off before.) Nothing happened! The difference in this trip was that it was about 78 degrees outside rather than 90+ degrees.

HEAT seems to be the factor. I drove 220 miles round trip before it got hot outside and never had a problem one. The day that I took it for a long drive in the heat, bam! (Both times.)

I guess that I will hope for a hot day next week when I am off again and I will go and rent the gauge from Auto zone. I'll keep you posted.
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Thursday, June 17th, 2010 AT 7:53 PM
Tiny
JAULT01
  • MEMBER
Scotty:

I replaced the fuel filter but the pressure is still reading in the 50's off of the rail. When I gas it, it does pop up to 60 and then backs off even while keeping the throttle open.

Since replacing the igniton wires and the plugs I haven't had any issues (the plugs were carbon fouled a bit) but then again I haven't been able to take a long drive when the weather is similar to the days that I had the problem.
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Thursday, June 24th, 2010 AT 1:55 PM
Tiny
JAULT01
  • MEMBER
Just drove 115 miles, it was sunny and 88 degrees. Still nothing.
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Thursday, June 24th, 2010 AT 5:27 PM

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